Hello guys,

I am flying a YS .63 in a pattern/3d aircraft. The tank is on the CG so there are no trim changes in flight. The tank is probably 12 inches from the engine.

I am just having a terrible time with it. First off, it has always leaked fuel from the carb after priming or running the engne until I get rid of the tank pressure, which I forget every once in a while.

It is VERY hard to get a consistant adjustment and the needles need to be tweaked after every flight if not between every flight. I have no trust in the engine. The engine has NEVER been run lean, but I have had many dead sticks. The few times I did some torque rolls (nose straight up) at 1/3 to 1/2 throttle the engine eventually dies after 10 seconds or so. It's just gotten worse.

Now I can't even start the engine. The one lucky time it started (After an hour with it) it ran a little and died (I am using an electric starter, not possible to start it without one!). After going through that a few times it eventually stayed running and ran OK, but transition was slow and it would die at an idle. Would also die with the nose up.

I can't start the engine now, so obviously I'm not going to be flying it. I would not trust it anyway.

A few things you guys might ask-

The plug is a brand new O.S. "F"
Fuel is Wildcat YS 20/20
Prop is a 13x6 APC
Engine is mounted inverted
Regulator has been completely cleaned out
Tank and lines are tight, NO leaks

So, what is going on? This thing ran like it should for only the first couple tanks (still leaked) and has just gotten worse. I spent a lot of money for the best engine in this size range (I'm thinking the Saito .72 might have been the way to go!). Everyone told me it was the best you can buy, I believed them and went and bought it.

What's going on here? What can I do? Is this my fault? Any similar experiences?

Any input is greatly appreciated.

Thanks,
Michael

Hi Micheal,

When you cleaned out your regulator, did you replace the plunger correctly? If this is misaligned, it may cause fuel dripping off the carb when engine is shut off.

Is your regulator screw flush with the housing?

Is there by any chance your engine is overheating because of in-cowl application?

When was the last time you adjusted the valves? (this may not be the cause of your problem but just checking)


Azhar

Michael,

You may also want to ask for Dave Shadel's assitance via the YS Engine support forum... My guess is that he'll want you to send it in so that he can look it over...

Are you using the stock exhaust, a flexible tube, or a tuned pipe? I seem to recall Dave saying this engine likes a little back pressure...

I am no expert on these engines, but I have at least one that runs better than anything else I have seen in its size class...

Thanks for the replies guys.

The carb dripped before I ever took the regulator apart and yes, I think I put it back together right.

Yes the screw is flush and I have tried turning it in or out with no affect.

Engine is far from overheating, it is barely warm after a flight. If I lean it out I just get more power, but nothing changes!

Valves have been adjusted.


I am using the muffler that came with the engine and I have not taken the baffle out.

I figured I would have to send it in, but I am doing whatever I can to prevent that! I'm sure YS repairs aren't cheap!!

Any other ideas?

try another new OS plug. you may have a duff one.

As soon as you noticed the carb dripping, you should have returned the engine for servicing. Something was obviously wrong. YS engines do not "drip" when they are right.

Perhaps you would have been better off with the Saito .72. YS engines are for those with meticulous mechanical skills. Nothing less will do.

If you just got the engine the repairs should all be under waranty so all you pay is to send it.

That is a common sign of a leaky check valve, replace it or clean it and I bet your problems disappear.

Yes to what Can 773 said and don't ever think you would have been better off with a Saito 72 . The 63 is a super engine and once dialed in it is very trouble free.

"YS engines are for those with meticulous mechanical skills. Nothing less will do."

Hehe, thanks for the encouraging words Artisan.

locoworks, I thought that was the problem to begin with which is why I went out and bought another brand new plug. No difference.

How does the check valve have anything to do with the carb leaking? I will check it anyway...

"The 63 is a super engine and once dialed in it is very trouble free."

That's why I got it!! I guess all that raw power had something to do with it too...

I'll admit, I've had a couple Saito's and they were also super engines with no trouble. May not have power like a YS, but they ran good!

I will go fiddle with it once more today and if it still get's mad at me I'll send her in.

Thanks again for all the replies.

Ditto!!!!!!!!!!!

Mine had the same symtoms. Called them. They said adjust the regulator and go to a 13-4 APC. I was running 13-6 APC.
Tried it, no luck. Sent it back!!!!!!!!!!!
Hope they know how to fix it. Dale

It's not the check valve. The check valve just ensures you hold pressure in the tank.

Since you have pressure in the tank fuel wants to flow through the carb unless your regulator stops it when not running. Something is wrong with the regulator... Probably need to send to YS.

By the way, you will be very happy with the ys.63 ... It's just outstanding - reliable, predictable, and powerful.

Sorry to hear about your misfortune.

Mike

Here's the update-

I ran it again today. I Richened up the low end needle and the engine started up easier and ran OK, but if kept at a low thottle setting the engine would eventually die (too rich). I shut it down and fuel just started pouring out of the carb...It was terrible! Turning the regulator in 1/2 a turn or more didn't work. I think this has something to do with the plunger in there, but we shall see.

I packed the engine up and will ship it over tomorrow. I hope their customer support is as good as their reputation!

It's a good thing it's windy, cold, and rainy over here. If it wasn't, I wouldn't be as relaxed about this!

Thanks again for the replies guys.

Dale, when did you send yours in?

"you will be very happy with the ys.63 ... It's just outstanding - reliable, predictable, and powerful."

If all goes well I'll be saying the same thing in a couple of weeks...

Clean the check valve, I guarantee you it will save you the trip back to YS, beleive me this is most likely your problem.

This has happend to me many times the cure is always the check valve.

My 91AC drips a bit but runs beautifully. I certainly am not meticulous, but I would say it has been one of the best running engines in our club if not the best and I picked it up used. I would love to run only YS based on my experience and will probably purchase more in the future. Have you tried a few different fuels? Mine wouldn't run on 2 stroke 15% nitro 18% oil and was I frustrated. It would throw the prop. On 4 stroke 15% nitro and 17% oil it is phenomenal.

How can this have anything to do with the check valve? That doesn't make any sense to me. How does that have any affect on fuel dripping out of the carb? Something is wrong with the engine...

I have used many different fuels with it and it has been the same on each one, just small power differences. Currently I have been using YS 20/20 from Wildcat...

4*60, Just one more reason why I bought this engine...

I am not trying to be a wiseguy. I am telling you the truth.

YS engines are great until a minor problem crops up. Most sport flyers are not meticulous enough to learn the drill. Maybe you are, but maybe you are not. I have no way of knowing.

I do know that any YS user that is intent upon using these engines will have to learn how the engines work at a level they never dreamed of before. Some would be better off with a simpler engine design, such as the Saito .72, or any non YS engine.

My only suggestion to those that still insist upon using YS engines, even though they lack the talent to maintain them, is to buy several so that they can keep one or two in the mail.

Well for a bit of antidotal evidence about the reliability and simplicity of YS engines. Currently have 5 different YS engines with the oldest about 4 years old. Fuel and go reliability...I've never had any major problem requiring service.

Sure, you do need to understand the fuel system, but other than that there the same. It's not like they're plasma power plants.

The engine which is of subject of this thread has a problem which I believe is related to the regulator. These issues will need to be resolved by someone qualified to repair the engine. The regulator on YS engines are responsible for controlling fuel flow during operation and when stopped. The check valves only responsibility is to ensure that pressure does not back escape from the fuel tank.

They are more complicated because they have a more sophisticated fuel system, but when it's working properly it's simple to setup and use. No more problems with a fuel tank which is not positioned properly, which has always annoyed me.

Just my opinion. Keep us posted on the solution.

Good luck.
Mike


.

Just give it a shot, it takes 2 minutes to check it out, but I promise you that is the problem. You can have it up and running tomorrow or you can wait 2 weeks for YS to service it, your choice.

I dont understand exactly why this causes this problem but after flying only YS engines for the past 10 years I have seen it enough to know that fuel pouring out of the carb after shutdown is almost 100% of the time a faulty check valve.

Yes and if it is faulty when the motor is shut down the pressure can flow back into the engine pushing the fuel that is in the motor out the carb, drip drip drip.

I had the same problem as you with (2) new YS 63 engines. The cause was a small speck of something in the check valve.

Clean your check valve as can773 suggested - then go fly.

I sent it 11/7 Thursday. They said turn around time was 7 to 10 days. Dale

How is it they heed the advice of people who say they (YS) are nothing but trouble and challenge the advice of those who have good sucsess ? Oh well I guess it is self explanatory !

Yes , a dirty regulator can cause the leakage but the check valve is an easier fix to try and it is the more common problem.

The YS is DIFFERENT than others and only harder for those who have a hard time adapting to DIFFERENT. Once set up they are very unfussy and NOTHING in their size and type runs as well , NOTHING>

Thanks for all the replies guys...

I appreciate it, even the ones who blame this on me.

I have checked the regulator and flushed it out and cleaned it off many times. There is nothing in it. The check valve has been cleaned and checked and is fine. This problem has existed since the very first run, It has just gotten worse. Dave at YS said it's a faulty plunger and they need to replace it... He also said it has been a problem on many newer YS .63's and they all need to have the new plunger put in, but for some reason they won't send them off seperately without fiddlin' with the engine.

The check valve theory still doesn't make any sense to me. If it can't hold pressure when the engine is off, it can't hold it when the engine is on so the pressure can't build up to begin with. Even if it turns out to be the check valve (small chance, IMO) I will feel MUCH better about running it and flying after I know the guys at YS have had a look. If it turns out to be the bad plunger in the regulator, I'll just have to come back and give all the check valve guys trouble...

Thanks again everyone. Keep it coming!

I agree with you... The check valve was deffinatly not the problem if the tank was holding pressure. ..... That's all the check valve does is to make the tank hold pressure. The check valve is the culprit when you have no pressure and/or the engie leans out... I would have guessed the problem to be in the regulator/plunger assembly as well.

Gotta be happy it wasn't you and was in fact a defect!